干旱区生态环境知识资源中心(Arid): Understanding groundwater salinization mechanisms to secure freshwater resources in the water-scarce city of Maputo, Mozambique

Arid

DOI	10.1016/j.scitotenv.2018.12.343
	Understanding groundwater salinization mechanisms to secure freshwater resources in the water-scarce city of Maputo, Mozambique
	Nogueira, G.1,3; Stigter, T. Y.1; Zhou, Y.1; Mussa, F.2; Juizo, D.2
通讯作者	Nogueira, G.
来源期刊	SCIENCE OF THE TOTAL ENVIRONMENT
ISSN	0048-9697
EISSN	1879-1026
出版年	2019
卷号	661 页码:723-736
英文摘要	In this study hydrochemical, isotopic and multivariate statistical tools are combined with a recharge analysis and existing geophysical data to improve understanding of major factors controlling freshwater occurrence and the origins of high salinities in the multi-layered coastal aquifer system of the Great Maputo area in Mozambique. Access to freshwater in this semi-arid area is limited by an inefficient public supply network, scarce surface waters, long droughts and an increasing population growth. Groundwater has a large potential to enhance water security, but its exploitation is threatened by both coastal and inland salinization mechanisms that are poorly understood. A GIS approach is utilized to classify potential recharge zones based on hydrogeological properties and land use/cover, whereas potential recharge rates are estimated through a root zone water balance method. In combination with water stable isotope data results reveal that extreme rainfall events provide the most relevant contributions to recharge, and interception and evaporation play an important role in the low recharge areas. Hierarchical clustering of hydrochemical and isotopic data allows the classification of six water groups, varying from fresh to brackish/salt waters. Corresponding scatter plots and PHREEQC modelling show evaporation and mixing with seawater (up to 5%) as major processes affecting salinity in the area. The co-occurrence of high alkalinity and Cl concentrations, in combination with piezometric and geo-electrical data, suggests that: 1) inland brackish/salt groundwater is caused by mixing with seawater trapped within clay layers; and 2) brackish/salt surface waters result from seepage of brackish groundwater into rivers and wetlands, followed by evaporation, hence increasing salinity and delta O-18 values. Mixing with small fractions of trapped seawater as main salinity source, rather than halite dissolution, is further corroborated by Br/Cl ratios of brackish/salt water samples near the ocean ratio. Cation exchange upon salinization is mainly observed in the semi-confined aquifer, while freshening takes place in the phreatic aquifer, particularly in areas presenting high recharge rates. (C) 2019 Elsevier B.V. All rights reserved.
英文关键词	Saltwater intrusion Old trapped seawater Evaporation Extreme rainfall recharge Hydrochemistry Semi-arid coastal aquifer
类型	Article
语种	英语
国家	Netherlands ; Mozambique ; Germany
收录类别	SCI-E
WOS记录号	WOS:000458408200067
WOS关键词	SHALLOW ALLUVIAL GROUNDWATER ; COASTAL AQUIFERS ; CHEMICAL EVOLUTION ; SEAWATER INTRUSION ; STABLE-ISOTOPES ; POTENTIAL ZONES ; MARINE WATER ; BASIN ; ORIGIN ; VALLEY
WOS类目	Environmental Sciences
WOS研究方向	Environmental Sciences & Ecology
资源类型	期刊论文
条目标识符	http://119.78.100.177/qdio/handle/2XILL650/218663
作者单位	1.IHE Delft Inst Water Educ, Dept Water Sci & Engn, NL-2611 AX Delft, Netherlands; 2.Univ Eduardo Mondlane, Dept Engn, Maputo 3453, Mozambique; 3.Helmholtz Zentrum Umweltforsch, Dept Hydrogeol, D-04318 Leipzig, Germany
推荐引用方式 GB/T 7714	Nogueira, G.,Stigter, T. Y.,Zhou, Y.,et al. Understanding groundwater salinization mechanisms to secure freshwater resources in the water-scarce city of Maputo, Mozambique[J],2019,661:723-736.
APA	Nogueira, G.,Stigter, T. Y.,Zhou, Y.,Mussa, F.,&Juizo, D..(2019).Understanding groundwater salinization mechanisms to secure freshwater resources in the water-scarce city of Maputo, Mozambique.SCIENCE OF THE TOTAL ENVIRONMENT,661,723-736.
MLA	Nogueira, G.,et al."Understanding groundwater salinization mechanisms to secure freshwater resources in the water-scarce city of Maputo, Mozambique".SCIENCE OF THE TOTAL ENVIRONMENT 661(2019):723-736.